One sunburn in childhood doubles your kid's risk for melanoma - the deadliest of skin cancers - later in life. That make's sunscreen a good thing. But which one should you use?

Sorting out sunscreens

Researchers in Australia — home to brilliant sun and some of the world’s highest melanoma rates — found in one big study that slathering sunscreen on every day cuts risk 50 percent. And regular use drops odds for invasive melanoma, the worst kind, by 70 percent. (AP Photo/Daniel Portnoy)

Sari Harrar

One sunburn in childhood doubles your kid’s risk for melanoma — the deadliest of skin cancers — later in life. So we send our kids to the pool, to camp, to the beach slathered in sunscreen, covered in sun-protection clothing and bathing suits made from sun-protection fabrics, topped with floppy hats they probably take off the minute we’re out of sight.

Sunscreen’s a good thing. A really good thing. Researchers in Australia — home to brilliant sun and some of the world’s highest melanoma rates — found in one big study that slathering it on every day cuts risk 50 percent. And regular use drops odds for invasive melanoma, the worst kind, by 70 percent.

More sunscreens than ever offer broad-spectrum protection against the sun’s UV-A and UV-B rays. That’s important, because both contribute to cancer. UV-A rays penetrate more deeply into the skin, dinging the DNA in deeper skin cells. UV-B rays harm upper layers of the skin.

But even sun-savvy Aussies are skipping sunscreen this year after new research raised concerns about some sunscreen ingredients.

There’s evidence that some ingredients in broad-spectrum sunscreens may pose health risks:

Oxybenzone: Found in 52 percent of sunscreens, this ingredient is absorbed by the skin and acted as a hormone disruptor in lab studies. It can also trigger allergic skin reactions.

Retinyl palmitate: Found in 25 percent of sunscreens, this ingredient is often added to prevent skin aging — not to block UV rays. But in animal studies, this form of vitamin A may speed the development of skin tumors and lesions when applied to skin in the presence of sunlight.

Nanoparticles of zinc and titanium oxides may be OK, however. While Consumer Reports has some reservations, the super-careful Environmental Working Group says that they’re safe and effective in sunscreen lotions. Tiny particles mean these sunscreens aren’t thick, pasty and white on the skin the way they used to be. And they act as “mineral filters” that block harmful UV rays without penetrating the skin, causing allergic reactions or disrupting hormones. “EWG’s review of more than a dozen in vivo and in vitro studies found little to no skin penetration for nanoparticle zinc oxide and titanium dioxide on healthy human, pig and rodent skins (EWG 2009),” the group says.

Choosing Sunscreen

But don’t skip sunscreens. Reviewers say there are still plenty out there that work safely. Here’s what to look for:

Broad-spectrum protection. Check the ingredients list for zinc oxide, titanium dioxide, avobenzone (3 percent) or Mexoryl SX. For brand recommendations, check the Consumer Reports guide (subscription required) or the Environmental Working Group guide. The EWG says they reviewed 262 studies and checked ingredients in 1,800 sunscreens. This year, 25 percent met their standards for safety and effectiveness — up from just 8 percent in 2011.

SPF 15 to 50. Go for a higher Sun Protection Factor for skin that burns easily. The EWG says higher SPF ratings don’t protect much better than SPF 50 and may give you a false sense of security about hanging out by the pool or on the beach in the middle of the day.

Lotions. Consumer Reports recommends avoiding spray sunscreens. They’re so convenient, but the FDA is currently investigating the risks of inhaling spray sunscreens — which may be greatest in kids. Use a spray if nothing else is available, but use it the way you would a lotion — spray it into your hand, then apply.

Water-resistant formulas. They stay on longer in the pool, ocean or when your kid is sweating. But it’s still important to reapply often and liberally.

Five Ways to Block the Sun

Use plenty of sunscreen. Apply about an ounce — enough to fill a shot glass. Most of us use one-fourth to one-half as much as we really need. Apply to dry skin 15 minutes before heading outside. Reapply every two hours, more frequently after swimming or heavy sweating.

Add lip balm. Use one with an SPF of 30 or higher. Lips can burn, and develop skin cancer, too.

Buy your kids sunglasses and hats, too. Let them help you choose.

Take a break. The sun’s rays are strongest from 10 am to 4 pm. Ducking indoors for lunch cuts exposure.

Keep babies out of the sun. The American Academy of Pediatrics recommends avoiding sun exposure for babies younger than six months. If you can’t avoid it, protect first with light, long-sleeved top, long pants and a hat with a grim. Dab a little sunscreen on baby’s face if necessary, but don’t use it on hands, arms, feet or any other body part your baby can get into her mouth.